Mixing capsule and method for activating the same

ABSTRACT

A mixing capsule for a two-component mixture comprises a preferably cylindrical container part ( 13 ). An axially displaceable piston ( 15 ) is guided within the container part ( 13 ). An opening ( 25 ) is provided on the front face of the piston ( 15 ) and leads into a liquid receptacle ( 23 ) with a burstable wall or membrane ( 29 ). The membrane ( 29 ) closes the opening ( 25 ) in the non-activated condition of the capsule ( 11 . The hollow ( 35 ) between the front faces of the container part ( 13 ) and the piston ( 15 ) constitutes a mixing chamber ( 35 ). The activation part ( 33 ) can be displaced by means of activation pin ( 37 ) that closes the discharge nozzle ( 19 ) in the non-activated condition. In the activated condition of the capsule the activation part ( 33 ) is to all intents and purposes completely accommodated within the liquid receptacle.

[0001] The invention relates to a mixing capsule a two-component mixtureand a method of activating a mixing capsule containing at least twocomponents of a multi-component mixture.

[0002] EPA-A-0 245 788 discloses a mixing capsule for a two-componentmixture with a cylindrical housing with an integrated discharge nozzleand a piston capable of moving axially within the cylindrical housing.The circumference of the piston is provided with a thread that canengage with a corresponding internal thread of the cylindrical housing.The front face of the piston has a central opening through which aliquid can flow into the interior of the piston. A liquid cushionarranged on the front face of the piston serves as liquid reservoir. Theliquid cushion is provided with a membrane adjacent to the front face ofthe piston that will burst (explode) in the event of an overpressure inthe region of the opening. The rear face of the piston is closed with aplug and the space within the piston serves to contain the pulverouscomponent of the two-component mixture. When the components are to bemixed, the piston is screwed into the housing until the membrane burstsand the liquid pours into the interior of the piston. The bursting ofthe membrane causes it to fray and parts of the membrane may find theirway into the mixing chamber.

[0003] A mixing capsule similar to EP-A-0-245788 is disclosed by U.S.Pat. No. 5,026,283. In this case, once again, the membrane separatingthe liquid package from the mixing chamber is made to burst by theapplication of an overpressure. Consequently, loose pieces of themembrane can reach the mixing chamber even with this capsule. If themixture is to be discharged, the front membrane of the liquid packagemust first be punctured from the rear with the hep of a pin arrangedanother piston.

[0004] A characteristic feature of the capsules described above is thatparts of the membrane can find their way into the mixing chamber andtherefore the mixture when the capsule is activated. Another drawback isthat the activation of the capsule causes an overpressure in the mixingchamber. The overpressure is due to the fact that an additional volume,namely the liquid, is pressed into the mixing chamber. But anoverpressure during the mixing has the effect that gas is pressed intothe mixture and that undesired gas bubbles can therefore form when it isdischarged.

[0005] The present invention sets out to make available a mixing capsulein which no membrane fragments can reach the mixing chamber when it isactivated. A further aim is to create a capsule that can be activatedwith a small energy consumption. Another object is to suggest a capsulein which the danger of bubble formation is small. Furthermore, it isproposed to make available a capsule that can be economically producedand charged.

[0006] A capsule in accordance with the invention is characterized inthat a movable activation part is provided in the hollow between thefaces of the container part and the piston that defines the mixingchamber. This capsule has the advantage that the activation partpunctures the membrane in the direction of the liquid and that nomembrane parts will therefore find their way into the mixing chamber.Furthermore, only a small force is needed to puncture the membrane.Accordingly, no threads have to be provided on the container part andthe piston. A further advantage is that the volume of the mixing chamberremains constant during the activation process, i.e. when the componentsstored in the mixing chamber and the liquid receptacle are broughttogether, and that no overpressure is therefore produced. Over and abovethe activation function, the activation part in accordance with theinvention also has the function of a displacement organ that removes theliquid component from the liquid receptacle. Advantageously, theactivation part substantially fits into the opening on the front face ofthe piston, i.e. the respective outer and inner diameters of the partand the opening are substantially identical. This has the advantage thatthe membrane is held by the activation part after the latter has beenpushed inwards and that no membrane fragments can therefore reach themixing chamber. Preferably, the activation part can be displaced bymeans of an activation pin that closes the discharge nozzle in thenon-activated condition.

[0007] Advantageously, the form of the activation part will be thecomplement of the liquid receptacle. Consequently, the activation partcan expel the liquid within the receptacle into the mixing chamber. Afurther advantage is that the membrane is fixed in the liquid receptacleby the activation or displacement part. Advantageously, the activationpart will be situated in the liquid receptacle after activation in sucha manner as to be substantially flush with the front face of the piston.This has the advantage that the piston can practically completelydischarge the finished mixture from the capsule.

[0008] Although in general principle the liquid receptacle may be apackage made from a foil, the liquid is preferably contained a liquidreceptacle formed on the piston. According to a particularly preferredembodiment, the piston is itself designed as the liquid receptacle orintegrally attached thereto. This is a simple construction and can beproduced at a correspondingly low cost. Advantageously, a membranecovering the opening is or can be applied to the front face of thepiston. Since the wall of the piston has a predetermined wall thickness,the foil can be readily welded onto the front face. When this is done,there is practically no danger that a part of the liquid couldevaporate. Advantageously, at least a gasket will be formed on the frontof the piston jacket. This assures the sealing of the mixing chamberdefined by the front faces container part and the piston.

[0009] Advantageously, the front part of the activation part is designedas a tip. This makes it possible for the foil closing the liquidreceptacle to be punctured with a small energy expenditure. According toa preferred embodiment, an overflow channel or gutter running in theaxial direction is provided on the jacket of the activation part. Theoverflow channel may prevent a pressure build-up in the liquidreceptacle, because the liquid can easily flow out. Furthermore, theoverflow channel can be dimensioned in such a manner as to enable evenviscous or sticky media to leave the liquid receptacle.

[0010] In basic principle the activation pin may be formed directly onthe activation part. In that case the activation part together with theactivation pin can be inserted into the container part from behind. Apreset breaking at the bottom of the activation part makes it possiblefor the activation pin to be separated and withdrawn after the mixingprocess, for example by turning it. According to a preferred embodiment,however, activation part and activation pin are designed as separateparts. In this embodiment it is advantageous to provide a recess on thebottom of the activation part as guide for the activation pin. Theactivation part can be fitted onto the activation that has previouslybeen inserted into the discharge nozzle. Advantageously, the activationpart is a filling body with a flat bottom. The filling body may be madeof plastic material and have a form that is complementary to the liquidreceptacle. Advantageously, the filling body will fit into the liquidreceptacle more or less flush with the front face of the piston.

[0011] According to a particularly preferred embodiment, the length ofthe activation pin is such that the piston of the filled mixing capsulemay be pulled back over a certain distance from a filling position to amixing position. The volume enlargement produces an underpressure in themixing chamber. This has the advantage that the mixture is degassedduring the mixing. Consequently, no bubbles will form when the mixtureis discharged.

[0012] Another object of the present invention is a method of mixing amixing capsule containing at least two components of a multi-componentmixture, characterized in that the membrane is destroyed by pushing amobile activation part provided inside the mixing chamber into theliquid receptacle. Since the membrane is pushed into the liquidreceptacle, there is no danger that parts of the membrane will findtheir way into the mixing chamber. Advantageously, the activation partpresses the liquid from the liquid receptacle into the mixing chamber.Preferably, the mixing chamber is enlarged before the mixing, so thatthe mixing process takes place at a reduced pressure. This has theadvantage that a degassing of the mixture may take place during themixing.

[0013] By way of example, the invention will now be described withreference to the figures, of which:

[0014]FIG. 1 shows a longitudinal section through a mixing capsule inaccordance with the invention in the filled position (initialcondition);

[0015]FIG. 2 shows the capsule of FIG. 1 in the activated condition(mixing position);

[0016]FIG. 3 shows the capsule of FIG. 2 after the activation pin hasbeen withdrawn (discharge position);

[0017]FIG. 4 shows a conical activation part;

[0018]FIG. 5 shows a second embodiment of a mixing capsule with anactivation part that can be fixed to the bottom of the container; and

[0019]FIG. 6 shows a perspective view of an embodiment of the activationpart 33 with annular projections on the bottom.

[0020] FIGS. 1 to 4 show a mixing capsule 11 in accordance with theinvention with an outer container part 13 and a piston 15 received inthe container part 15. The piston 15 can be axially displaced in thecontainer part 13 and in FIG. 1 is shown in the initial or filledposition, while FIG. 2 shows it in the mixing position (activatedcondition of the capsule). The container part 13 is cylindrical and hasan opening 16 for the insertion of the piston is and a front face 17 onwhich there is formed a discharge nozzle 19. An annular groove 21 isprovided on the outside at the rear end of the container part. Theannular groove 21 serves to engage with the jaw of a discharge tool wellknown to persons skilled in the art.

[0021] A liquid receptacle 23 is provided on the piston 15. According tothe advantageous embodiment here shown, the piston 15 has the shape of acup with an opening 25 and an internal space 27. The internal space 27serves to accommodate the liquid component of a two-component resins andserves as a liquid receptacle 23 of stable shape. The opening 25 isclosed by a foil or membrane 29 when in the non-activated state. Thefoil is welded in a known manner onto the front face 31 of the piston15. One or more annular gaskets 32 are formed on the piston jacket toprovide a seal between the piston 15 and the container part 13. Thefirst gasket 32 is situated at the forward edge of the piston. Twofurther gasket 32 a, 32 b are situated at some distance from the firstgasket 32.

[0022] When the mixing capsule is assembled, a mixing chamber 35 isdefined between the front face of the piston 15 and the container part13. An activation part 33 is inserted in the mixing chamber between thefront faces of the piston 15 and the container part 13. The activationpart 33 is preferably designed as a displacement body having a shapethat is complementary the interior space 27. By means of an activationpin 37 accommodated in the discharge nozzle, the activation part 33 canbe axially displaced within the container part 13. The length of theactivation pin 37 is at least such as to make it possible for theactivation part 33 to be pushed completely into the liquid receptacle.The activation pin 37 has a head 38 that serves as a stop. The head 38has an undercut 40 in which the front end of the discharge nozzle canbecomes accommodated when the activation pin 37 is pushed fully inwards.

[0023] The bottom 39 of the activation part 33 is provided with a roundrecess 41. The recess 41 serves to accommodate the front part of theactivation pin 37. Advantageously, the front part of the activation pin37 and the recess 41 are designed in such a manner as to realize afriction joint. The activation part 33 is thereby fixed in the mixingchamber of the non-activated capsule 11. But one can also think ofproviding the activation part with radially projecting arms, so that itwill be guided inside the container part 13. With a view to assuringthat the liquid present in the liquid receptacle can flow into themixing chamber 35 without hindrance, an overflow channel 43 is providedin the jacket of the activation part (FIG. 4).

[0024] A modified embodiment of the activation part 33 envisages theprovision on the bottom of the activation part of means to fix theactivation part 33 in a detachable manner to the container part 13. Asshown in FIGS. 5 and 6, these means can be annular projections 47 thatcan engage with an annular groove 49 in the container bottom 51. Theannular groove 49 is provided around the opening of the discharge nozzle19. The shown embodiment has the advantage that when the capsule isfilled, the activation may first be inserted in the container part 13and that thereafter an undesired drop-out or sliding is prevented by thefriction connection between the annular groove 49 and the projections47.

[0025] The mixing capsule in accordance with the invention is preparedand used as follows: The activation and displacement part 33 is firsinserted in the container part 13 and the activation pin is then pushedinwards through the discharge nozzle 19 until the front part of theactivation pin becomes accommodated in the recess 41. Subsequently, asynthetic resin component (pulverous or liquid) is filled into thevertically oriented container part 13.

[0026] The piston 15, which also serves as the liquid receptacle 23, isfilled with the desired liquid in a separate operation and then tightlysealed. These processes can be performed in an automated manner. Thefilling of the piston 15 through the opening 25 and the welding of thefoil to the edge of the piston by means of hot punch can be very readilybe performed from above.

[0027] Thereafter the piston is inserted into the container part 13.With a view to avoiding a pressure build-up in the mixing chamber, awire may be inserted between the container wall and the piston, so thatair can escape from the mixing chamber when the piston is introduced.The wire can then be removed again. The position of the piston 15 in thecontainer part 13 is preferably chosen in such a manner that the piston15 of the filled mixing capsule can be moved rearwards (outwards) over acertain distance from an initial position (FIG. 1) to a mixing position(FIG. 2). Given the enlarged volume in the mixing position, a lowpressure will be created in the mixing chamber. This can be utilized fordegassing the mixture during the mixing process. For mixing purposes thecapsule is inserted into a known shaking apparatus. This shakingapparatus is provided with two retaining forks arranged at a certaindistance from each other and pre-tensioned in opposite directions. Thecapsule to be mixed is inserted between the forks.

[0028] When the capsule 11 is to be activated, the activation body 33 isfirst pushed into the liquid receptacle 23 with the help of theactivation pin 37, after which the entire piston 15 is displaced intothe mixing position. When this is done, the spiked displacement body 33punctures the foil 29 at the centre and presses the liquid syntheticresin component contained in the liquid receptacle into the mixingchamber 35. In the mixing position it then assumes the capsule 11 isshaken in a known shaking apparatus for a certain period of time. Theactivation pin 37 is then withdrawn and the finished viscous syntheticresin mixture is discharged with a known discharge pistol.

[0029] A mixing capsule for a two-component mixture will preferably havea cylindrical container part 13 with a discharge nozzle formed on thefront face. A piston is displaceably guided in the container part. Anopening is provided on the front face of the piston and leads into aliquid receptacle with a burstable wall or membrane. The membrane closesthe opening in the non-activated condition of the capsule. The hollowbetween the front faces of the container part and the piston constitutesa mixing chamber. A mobile activation part is provided inside the mixingchamber. The activation part can be displaced by means of an activationpin that closes the discharge nozzle in the non-activated condition. Inthe activated condition of the capsule the activation part is to allintents and purposes completely inserted in the liquid receptacle. Thecontainer part 13 and the piston 15 are made of a suitable plasticmaterial.

[0030] The mixing capsule in accordance with the invention can beeconomically produced and filled. It has the advantage that no membraneparts can find their way into the mixing chamber. Furthermore, theentire liquid quantity is always pressed into the mixing chamber, sothat a constant quality of the mixings is obtained. Since the capsule isdevoid of both threads and undercuts, there is no danger that liquid maybe retained in these positions. The edge on the front face of the pistonmay constitute the filling opening. Given the sufficiently wide contactsurface of this edge, foils can be welded onto it a problem-free manner.The piston that serves as liquid receptacle can therefore be filled alsowith slightly volatile components.

[0031] Legend

[0032]11 Mixing capsule

[0033]13 Container part

[0034]15 Piston

[0035]16 Opening in the container part 13 for the insertion of thepiston 15

[0036]17 Front face of the container part

[0037]19 Discharge nozzle

[0038]21 Annular groove

[0039]23 Liquid receptacle

[0040]25 Opening (transit opening)

[0041]27 Internal space

[0042]29 Foil or membrane

[0043]31 Front face of piston

[0044]32 Gasket ring or sealing bulge

[0045]32 a, 32 b Second and third gasket rings

[0046]33 Activation part

[0047]35 Mixing chamber

[0048]37 Activation pin

[0049]38 Read of the activation pin

[0050]39 Bottom of the activation part (=displacement body)

[0051]40 undercut on the head 38

[0052]41 Recess

[0053]43 Overflow channel

[0054]45 Bottom of the activation part 33

[0055]47 Projections, for example of annular shape

[0056]49 Annular groove

[0057]51 Bottom of container

1. A mixing capsule for a two-component mixture with a preferablycylindrical container part with an opening and a front face situatedopposite it on which front face there is formed a discharge nozzle, apiston that can be axially displaced inside the container part, andopening in the front face of the piston, a receptacle for receiving aliquid being arranged on the pistons with a burstable wall or membranethat closes the opening in the non-activated condition of the capsule,characterized in that in the hollow between the front faces of thecontainer part and the piston there is provided a displaceabledisplacement body having a shape which is complementary to the liquidreceptacle.
 2. A mixing capsule in accordance with claim 1,characterized in that the activation part fits essentially into theopening.
 3. A mixing capsule in accordance with claim 1 or claim 2,characterized in that the activation part has a shape that iscomplementary to the liquid receptacle.
 4. A mixing capsule inaccordance with claim 1, characterized in that in the activatedcondition of the capsule the activation part is accommodated in theliquid receptacle substantially flush with the front face of the piston.5. A mixing capsule in accordance with claim 1, characterized in thatthe piston constitutes the liquid receptacle.
 6. A mixing capsule inaccordance with claim 1, characterized in that a membrane covering theopening is attached to the front face of the piston.
 7. A mixing capsulein accordance with claim 6, characterized in that the membrane weldedonto the piston.
 8. A mixing capsule in accordance with claim 1,characterized in that at least one gasket ring or sealing bulge isformed on the piston jacket.
 9. A mixing capsule in accordance withclaim 1, characterized in that the front part of the activation part isdesigned as tapering into a tip.
 10. A mixing capsule in accordance withclaim 1, characterized in that an overflow channel extending in theaxial direction is provided on the jacket of the activation part.
 11. Amixing capsule in accordance with claim 1, characterized in that theactivation part can be displaced by means of activation pin that closesthe discharge nozzle in the non-activated condition.
 12. A mixingcapsule in accordance with claim 11, characterized in that theactivation part is integral with the activation pin.
 13. A mixingcapsule in accordance with claim 11, characterized in that apredetermined breaking point is provided between the activation part andthe activation pin.
 14. A mixing capsule in accordance with claim 1,characterized in that a recess that serves as a guide for the activationpin is provided on the bottom of the activation part.
 15. A mixingcapsule in accordance with claim 1, characterized in that the activationpart is a filling body with a flat bottom.
 16. A method of activating amixing capsule for receiving at least two components of amulti-component mixture with a preferably cylindrical containing partwith an opening and a front face, on which there is formed a dischargenozzle, a piston that can be axially displaced inside the housing, anopening in the front face of the piston, a receptacle for receiving aliquid being arranged in or on the piston with a burstable wall ormembrane that closes the opening in the non-activated condition of thecapsule in which method a membrane or foil that separates the mixingchamber containing a pulverous component from the liquid receptacle isdestroyed and the content of the liquid receptacle is pressed into themixing chamber, characterized in that the membrane is destroyed bypushing a displaceable displacement body having a shape which iscomplementary to the liquid receptacle into the liquid receptacle. 17.Method of activating a mixing capsule for receiving at least twocomponents of a multi-component mixture with a preferably cylindricalcontaining part with an opening and a front faces, on which there isformed a discharge nozzle, a piston that can be axially displaced insidethe housing, an opening in the front face of the piston, a liquidreceptacle arranged in or on the piston with a burstable wall ormembrane that closes the opening in the non-activated condition of thecapsule, in which method a membrane or foil that separates the mixingchamber containing a pulverous component from the liquid receptacle isdestroyed and the content of the liquid receptacle is pressed into themixing chamber, characterized in that the membrane is destroyed bypushing a displaceable activation part into the liquid receptacle.
 18. Amethod in accordance with claim 17, characterized in that the activationpart presses the liquid from the liquid receptacle into the mixingchamber.
 19. A method in accordance with claim 17, characterized in thatmixing chamber is enlarged before the mixing, so that the mixing processtakes place in low-pressure conditions.